ABSTRACT The objective of this R03 proposal is to examine the benefit of triage to a trauma center for injured older adults, whether this benefit is heterogeneous according to clinical characteristics, and whether differences in survival following complications explain why trauma center care has not been as beneficial for older adults as it has been for younger adults. This is a significant area of inquiry because injury is the leading cause of loss of independence in older adults, also accounting for over 840,000 hospitalizations, 80,000 deaths, and $63.9 billion in costs in 2013. Triage and treatment in a trauma center have been shown to reduce mortality from serious injuries by at least 25% in patients under 55. However, the evidence base for the benefit of trauma center care for older adults is limited, even though injury mortality increases exponentially after the age of 55. This lack of evidence is problematic given: 1) current triage guidelines consider an age > 55 as a special consideration for triage to a trauma center despite the paucity of evidence for this approach; and 2) the majority of injured elderly adults prefer to be transported by EMS to their local hospital. Our long-term goal is to apply a ?precision medicine? approach to the care of injured older adults by leveraging population-level databases to guide the real-time determination of whether injured older adults would benefit from trauma center care based on their clinical characteristics. We also seek to identify what inhospital care processes are most needed to increase healthy survival. In this proposal, we will use a previously created dataset from a prior R01 to analyze all injured adults > 55 years old (N=31,884) with linked prehospital EMS electronic records, hospital data, and death certificates from New Jersey (2009-10). Our aims are to: (1) determine whether 60- day mortality for all and specific subgroups of injured older adults differs by EMS transport to a trauma center vs. non-trauma center; and (2) explore whether complication rates and 60-day mortality for injured older adults with complications differ by EMS transport to a trauma center vs. non-trauma center. This work is high impact because it will (1) yield a well-powered, unbiased estimate of the association between EMS triage to a trauma center and clinical outcomes for older adults; and (2) it will benchmark, for the first time, complication- associated mortality rates in trauma centers and non-trauma centers. The approach is innovative because it uses linked prehospital physiologic data with hospital and death certificate data to examine variation in outcomes in statewide cohort of injured older adults and it will use instrumental variable modeling adjust for unmeasured confounding. The proposed research is significant because our findings will enable the further development and testing of revised, more precise trauma triage protocols, and it will provide actionable targets for inpatient care quality improvement. This has the potential to improve the effectiveness, efficiency, and patient-centeredness of field triage, by elucidating the trauma center treatment benefit among older adults.